Optical communication systems increasingly employ wavelength division multiplexing (WDM) techniques to transmit multiple information signals on the same fiber, and differentiate each user sub-channel by modulating a unique wavelength of light. WDM techniques are being used to meet the increasing demands for improved speed and bandwidth in optical transmission applications. In optical communication networks, such as those employing WDM techniques, individual optical signals are often selectively routed to different destinations. Thus, a high capacity matrix or cross-connect switch is often employed to selectively route signals through interconnected nodes in a communication network.
Optical switches typically allocate an entire wavelength to each packet in order to permit wavelength selective routing. Wavelengths that can be exploited for optical communications, however, are finite in number and expensive to provision. Thus, an entire wavelength is a rather large granularity for resource allocation in an optical communication system. U.S. patent application Ser. No. 10/306,935, entitled “Optical Packet Tray Router,” discloses an optical packet tray router that aggregates one or more packets in a packet tray for transmission over a network. The packet trays provide a mechanism for switching at the wavelength level. The packet trays carry one or more packets through an optical communication system and represent the routable entity with a finer grain size than wavelength circuit switched systems, since each packet tray can be dynamically, in time and space, assigned a unique wavelength.
While the packet trays provide an efficient mechanism for switching optical signals at the wavelength level, challenges remain for effectively mapping user information onto network resources using state-of-the-art nodal technology. For high rate, long-lived, flows of information, the packetization process and the packet switching process further increases nodal real-time and routing complexity. A need therefore exists for methods and apparatus for optical communications that provide freedom from packetization in the time dimension and freedom from adherence to a defined wavelength grid, such as the International Telecommunication Union (ITU) grid, in the wavelength dimension.